JPH1174889A - Topology modification method - Google Patents

Abstract

(57) [Summary] [Problem] To enable communication only by processing by hardware when a communication node is erroneously arranged in a loop where communication nodes cannot be communicated in a state where the communication nodes are laid out in a loop according to IEEE1394 or the like. Provides a topology modification method. When a communication node is determined to be included in a loop in a loop detection step, a logical connection between the nodes is once invalidated. When the connection notification is transmitted to the adjacent communication node that is physically connected in the connection step 2 and forms the loop, and the connection notification is also received from the adjacent communication node,
It is determined that connection is possible without logically forming a loop. Communication nodes determined to be connectable form a node group having the same tree or daisy chain structure. When the node group increases the number of communication nodes as components, the entire bus becomes one node group, and the bus is recognized as a tree or a daisy chain, and communication becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed serial bus standard, such as IEEE 1394, in which communication is disabled when a communication node is arranged in a loop. And a topology correction method for correcting the topology.

[0002]

2. Description of the Related Art Generally, when communication nodes are arranged in a loop on a bus, there is a danger that data with different routes will collide during data transfer. In a network having a loop (star) arrangement, such as 10BASE-T defined in IEEE802.3, a switch determines a data transfer path and manages port connections so that a collision does not occur. , Increasing the efficiency of data transfer. Also, L
In connection between ANs and the like, a loop-free arrangement having a logical tree structure is adopted by a spanning tree algorithm defined in IEEE 802.1.

[0003]

SUMMARY OF THE INVENTION
Hosts and switches that perform address assignment, data transfer path management, and topology management are required, and all communication nodes are equal, and the interface specified by IEEE 1394 or the like must communicate without a host. Is not applicable. However, IEEE13
According to the provision of 94, the maximum number of available communication nodes is 63,
Since the number of ports is as large as 16 per communication node, there is a high possibility that a user will mistakenly arrange communication nodes in a loop, and in such a case, communication becomes impossible.

According to the IEEE 1394 regulations, in such a case, it is not possible to obtain information such as which communication node is incapable of communication from the bus, and it is necessary for the user to directly check the wiring and change the connection. . Therefore, an object of the present invention is to provide a topology correction method that can automatically restart communication from a state where communication is disabled due to a loop arrangement.

[0005]

SUMMARY OF THE INVENTION According to the present invention, when communication is disabled due to the arrangement of a loop, the connection in the loop is logically invalidated once, and the communication nodes in the loop do not form a loop. That the connection points can be determined without excess or shortage by reconnecting in such a way that the buses physically arranged in a loop can be logically recognized as a tree or daisy chain, and communication is automatically resumed It is to let.

The following is a description of each claim. The topology correction method according to claim 1, wherein a bus configured by a plurality of communication nodes and a transmission path connecting the communication nodes,
When the communication nodes are connected in an arrangement including a loop by a transmission line, each communication node determines whether or not the communication node is included in the loop in a loop detection step. Logically invalidates the connection, and in the connection step, among the communication nodes connected by the transmission path, transmits a connection notification to an adjacent communication node forming a loop, and logically loops. It is characterized in that it is determined whether or not a connection can be made with an adjacent communication node without forming a logical connection, and a logical connection is made valid at a place where it is determined that the connection is possible.

In the system according to the first aspect, if it is determined in the loop detecting step that the communication node forms a loop, the connection between the communication nodes by the transmission line is logically invalidated once, and the loop is set in the connection step. A bus including a loop arrangement is physically determined by determining whether connection is possible without forming a logical loop with an adjacent communication node constituting the connection path, and validating only the connection on the transmission path determined to be connectable. Is recognized as a tree or a daisy chain so that communication can be performed.

According to a second aspect of the present invention, in the topology modification method according to the first aspect, in the connection step, the adjacent communication node also transmits the connection notification on the transmission line on which the communication node in the loop transmits the connection notification. When transmitting, it is determined that it is possible to connect to an adjacent communication node without logically forming a loop. In the method according to the second aspect, in the connection step, whether or not connection with an adjacent communication node is possible is determined by determining that both communication nodes on both sides of the same transmission path have notified the connection, and the communication is performed on the transmission path. Less information.

According to a third aspect of the present invention, in the topology correction method of the first aspect, in the connection step, the intra-loop communication node can be newly connected to an adjacent communication node without logically forming a loop. If it is determined, the node group formed by connectable communication nodes already formed by the in-loop communication node and the node group formed by the adjacent communication node newly determined to be connectable are newly added. Form the same node group in
A connection notification is transmitted from one node group at a maximum of one port.

In the method according to the third aspect, the communication nodes determined to be connectable belong to the same node group,
By notifying a connection from only one port from one node group, a loop is prevented from being formed in the process of reconfiguring the topology without exchanging information with a remote node. According to a fourth aspect of the present invention, in the topology correction method according to the first aspect, when the communication node in the loop has one or more ports that cannot be connected to the adjacent communication node in the connection notification point determination step, the connection is established. A connection request for requesting to become a communication node that performs notification is made, and after transmitting the connection request, if it is determined that connection notification is possible, the process proceeds to a connection step.

In the method according to the fourth aspect, in the connection notification point determining step, the node in the loop having a port forming a loop that is not yet connectable to the adjacent communication node transmits a connection request, so that the node group can be transmitted in a short time. The node candidates for which connection notification is to be made are determined. According to a fifth aspect of the present invention, in the topology correction method according to the fourth aspect, in the connection notification location determining step, the connection request is received when the communication node in the loop receives the connection request before transmitting the connection request. A connection request is transmitted from a port that forms a loop other than the loop request.

In the method according to the fifth aspect, in the connection notification location determining step, the request of the communication node which has made the connection request first is prioritized and repeated to another adjacent communication node, whereby a large amount of information is provided. The request is propagated and arbitrated at high speed over the transmission path that does not exist. According to a sixth aspect of the present invention, in the topology correction method according to the fourth aspect, in the connection notification location determining step, when the communication permission in all the ports to which the in-loop communication nodes have transmitted the connection request has received the connection request, If a connection request from an adjacent communication node has not been received prior to sending a connection request, it is determined that connection notification is possible, and the process proceeds to the connection step. If received, connection is permitted at the port that received the connection request. Is transmitted.

[0013] In the method according to claim 6, in the connection notification location determining step, connection permission is given to all communication nodes in the direction in which the connection request is repeated, and connection notification is performed, so that connection notification is performed without determining a route or the like. Is determined. According to a seventh aspect of the present invention, in the topology correction method according to the fourth aspect, in the connection notification location determination step, when one port receives the connection request and there is no other port constituting a loop. The connection permission is transmitted at the port receiving the connection request.

[0014] In the system according to the seventh aspect, in the connection notification location determining step, the connection permission is started from a communication node to which the connection request is not repeated, thereby determining the node to which the connection notification is performed without determining the route or the like. I do. In the topology correction method according to the eighth aspect, in the topology correction method according to the fourth aspect, when it is determined in the connection notification location determining step that a plurality of connection requests are received simultaneously, the connection request is received at the port that received the connection request. Is transmitted.

In the system according to the eighth aspect, in the connection notification location determining step, the connection request is transmitted to the communication node that has made the connection request at the same time, and a request contention state is created to retry the request. Let it. In the topology correction method according to the ninth aspect, in the topology correction method according to the fourth aspect, when a conflict of the connection request is observed at the port that transmitted the connection request in the connection notification point determination step, the transmission of the connection request is performed by itself. The in-loop communication node that has started stops transmitting at the port that has transmitted the connection request for a standby time selected based on the random number given by the random number generating means.

In the method according to the ninth aspect of the present invention, in the connection notification location determination step, the random number generation means randomly determines the waiting time until the connection request is resumed from the observation of the connection request competition, thereby arbitrating the connection request. Eliminate regularity of results.
According to a tenth aspect of the present invention, in the topology correcting method according to the ninth aspect, the difference between the standby times selected based on the random number given by the random number generating means in the connection notification point determining step is the longest of the bus. It is characterized in that the time is longer than the time required for a signal to reciprocate on a transmission path having a length corresponding to the path.

In the system according to the tenth aspect, in the connection notification location determination step, a difference in a waiting time from the observation of the conflict of the selected connection request to the restart of the connection request is determined between the communication nodes farthest apart on the bus. The time sufficient to repeat the signal back and forth ensures that the winning or losing of the competition is determined when the selection result of the waiting time is different. In the topology correction method according to the eleventh aspect, in the topology correction method according to the first aspect, in the connection notification point determination step, a local root node is determined in the node group, and a connection request is issued to the local root node. Perform the transmission of the connection permission by the local root node.

In the system according to the eleventh aspect, the connection notification location determining step determines a local root node in the node group, thereby arbitrating connection requests from a large number of communication nodes at a high speed. In the topology correction method according to the twelfth aspect, in the topology correction method according to the fourth aspect, when the connection notification is enabled in the connection notification location determination step, the port that performs the connection notification is a port constituting a loop, and It is characterized in that selection is made from a port that is not in a connectable state based on a random number given by a random number generating means.

According to the twelfth aspect of the present invention, in the connecting step, the port for transmitting the connection notification is selected from among ports constituting a loop having no connectable adjacent communication node.
By randomly determining using random number generation means,
Eliminates the regularity of the port selected as the connection notification port. The topology correction method according to the thirteenth aspect is directed to the first aspect.
In the above described topology modification method, the waiting time in the waiting step is determined from a plurality of times based on a random number given by the random number generating means.

In the method according to the thirteenth aspect, in the waiting step, the waiting time is randomly determined by using a random number generating means, thereby eliminating the regularity of the node selected as the connection notification node. According to a fourteenth aspect of the present invention, there is provided the topology modification method according to the first aspect, further comprising a connection confirmation step immediately after the connection step, wherein the connection confirmation step determines whether connection with an adjacent communication node is possible. When it is determined in the immediately preceding connection step that connection with the adjacent communication node is possible, the adjacent communication node transmits a connection confirmation for determining that connection with itself is possible.

In the method according to the fourteenth aspect, a connection confirmation is transmitted from a port determined to be connectable to an adjacent communication node, and it is determined in the connection confirmation step whether connection with the adjacent communication node is possible. Of the possibility of connection due to the phase shift of the clocks. The topology correction method according to claim 15 is a method according to claim 1.
In the described topology correction method, if a time required for the topology correction has elapsed since the loop was detected in the loop detection step, the process of the topology correction is terminated.

In the system according to the fifteenth aspect, by terminating the topology correction processing after a lapse of a predetermined time from the time of detecting the loop, the processing is completed without exchanging information between distant communication nodes.

[0023]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. The following description is given on the assumption that the current topology correction method is realized by the cable physical layer defined by IEEE 1394, taking into account the restrictions of IEEE 1394.

First, the process of reconstructing the topology by the topology correction method of the present invention will be described in the order of FIGS. FIG. 2 shows a state in which the communication nodes 100, 101, and 102 are arranged in a loop. 103 to 108 are ports, and 110 to 112 are transmission lines. FIG. 3 shows that each of the communication nodes 100, 101, and 102 detects that they are arranged in a loop, and that each of the transmission lines 1 connecting the nodes is connected.
This shows a state in which connections for 10, 111, and 112 are logically invalidated. In this way, once all connections in the loop are invalidated, the IEEE 139
Because all the nodes do not require a host and all the nodes have the same interface, if an attempt is made to communicate by making a partially invalid portion, a plurality of communication nodes operate in the same way, This is because there is a possibility that an isolated communication node separated from the communication node may be formed.

FIG. 4 shows the communication nodes 100 and 10
1 shows a state in which connection notifications 115 and 116 are transmitted from the ports 104 and 106, respectively. Thus, at the stage where the adjacent communication nodes have not transmitted the connection notification on the same transmission path, it is not yet determined that the connection is logically possible. FIG. 5 shows that the communication node 101 of the communication node 100 and the communication node 101 changes the port for transmitting the connection notification, and the port 104 and the port 105 respectively.
Shows a state in which connection notifications 117 and 118 are being transmitted from. Thus, at the stage where the adjacent communication nodes are transmitting the connection notification on the same transmission path, the adjacent communication nodes 100 and 101 determine that connection is possible without forming a loop. Such a portion, here, the transmission line 110 is indicated by a solid line.

FIG. 6 shows a communication node 1 determined to be connectable.
00 and the communication node 101 are one node group 11
3 shows a state in which 3 is formed. Of course, this node group is logical when you look at the whole bus,
Actually, each communication node has only information on which adjacent communication node can be connected. FIG. 7 shows the communication node 10
1 is transmitting and receiving connection notifications 119 and 120 with the communication node 102 in order to further increase the number of communication nodes that can be connected. There must be one connection notification sent from one node group. This is to eliminate the risk that a loop is formed by connecting within the same node group.

FIG. 8 shows the communication nodes 100 and 10 of the entire bus.
1 and 102 have formed the same node group 114. Since the node groups 114 are arranged in a daisy chain, data transfer can be performed by determining a logical connection relationship in this state. After this, the connection notification is transmitted from the port 103 or the port 108, but is not transmitted at the same time, so that the problem of making a connection and forming a loop does not occur.

In the following, a control method of each communication node for performing the above processing will be described. FIG. 1 shows a flowchart of a control method of each communication node in the embodiment of the present invention. The loop detection step 1 is based on I
Tree- of the state of the physical layer specified by EEE1394
Corresponds to ID Start. In this case, if a signal called RX_PARENT_NOTIFY is not received by all ports physically connected to the cable or all ports except one after a bus reset for a certain period of time or longer, the communication node may be placed in a loop. It is decided to detect that it is being done.

It is determined whether or not a loop has been detected in the loop detection determining step 6. If no loop arrangement is detected in the loop detecting step 1, the initialization operation specified by the standard is continued (initialization phase). If a loop is detected, the process enters the topology modification phase 10 described below. At the time of transition to the topology modification phase 10, the connection flag set based on the physical connection of each port is cleared and the connection is logically invalidated. Ports that have not received RX_PARENT_NOTIFY while being physically connected in the loop detection step 1 are regarded as ports constituting a loop, and signal exchange in the topology modification phase 10 is performed only through this port. , Signals observed at other ports are ignored.

The topology correction phase 10 includes a connection step 2, a connection confirmation step 3, a standby step 4, a connection notification location determination step 5, a correction completion time determination step 7, and a connection notification determination step 8. The connection step 2 is a step of establishing a logical connection relationship with another communication node. Here, each communication node transmits a connection notification (TX_CONNECT_NOTIFY) from any one of the ports constituting the loop. ). When there are a plurality of candidates for this port, it is desirable to select the port as randomly as possible. This is because if there is a regularity in the order of performing the connection notification, there is a possibility that an infinite loop in which both connection notification locations do not match. Therefore, the port is determined by, for example, taking the modulo of the random number given by the random number generating means (the remainder obtained by dividing the random number by the number of ports constituting an unconnected loop).

In the cable physical layer defined by IEEE 1394, signals are exchanged using two twisted pair cables of AB as a transmission path. Each set of AB takes three states of 1, 0, and Z (high impedance), and the A port of one communication node is connected to the B port of the other communication node. Therefore, the signal transmitted from one communication node is AB-inverted and received by the other communication node.

The connection notification (TX_CONNECT) referred to here
T_NOTIFY) can be represented by a line state of A = Z, B = 0. In the connection step 2, this connection notification is transmitted, and it is determined whether or not the port performing the connection notification can connect to the adjacent communication node by connecting the cable (RX_CONNECT).
Is determined by whether or not received. Connection valid (RX_CONNE
CT) is a line state of A = 0, B = 0, and is a port that is performing connection notification, and an adjacent communication node is also notified of connection or connection confirmation (TX_CON) described later.
(NECT_CONFIRM, A = 0, B = 0). When the connection validity is received at the port that has performed the connection notification, the connection confirmation (TX_CONNE) is performed between the connection step 2 and the connection confirmation step 3 thereafter.
CT_CONFIRM). Then, irrespective of whether or not the connection validity is received, the process proceeds to the connection confirmation step 3 after a lapse of a predetermined time from the connection step 2.

In the connection step 2 and the connection confirmation step 3, the connection confirmation (TX_CONNECT_CON
The FIRM) transmission operation is basically the same, and the only difference between the two steps is that the connection notification is transmitted in the connection step 2 and the connection notification is not performed in the connection confirmation step 3. The connection confirmation step 3 is a step for preventing a possibility that the communication nodes at both ends of the communication node may determine that the connection is possible at the same location due to a phase shift between the communication nodes. Here, if it is determined in the immediately preceding connection step 2 that connection with the adjacent communication node is possible, a connection confirmation is transmitted. This prevents a risk that an adjacent communication node determined to be connectable cannot remain determined to be connectable to this node.
In the example shown in FIG. 9, the communication node 0 determines that connection is possible, and transmits a connection confirmation in the connection confirmation step 121. In FIG. 9, reference numeral 120 denotes a connection step of the communication node 0, and reference numeral 122 denotes a standby step of the communication node 0. Reference numeral 123 denotes a connection step of the communication node 1.

If it is not determined in the immediately preceding connection step 2 that connection with the adjacent communication node is possible, nothing is transmitted (A = Z, B = Z). Further, the determination as to whether or not the connection was possible with the adjacent communication node at the port for which the connection notification was performed in the immediately preceding connection step 2 is continuously performed, and although the adjacent communication node has determined that the connection is possible, the connection cannot be determined by itself. No misjudgment occurs even in the case of transition to the confirmation step. In the example shown in FIG. 10, in the connection confirmation step 125,
The connection confirmation transmitted by the communication node 1 is received, and it is determined that the connection is possible. In FIG. 10, reference numeral 124 denotes a connection step of the communication node 0, 126 denotes a standby step of the communication node 0, and 127 denotes a connection step of the communication node 1.

After a certain time has passed from the connection confirmation step 3, the process proceeds to the waiting step 4. By seeing the odd or even number of the random number given by the random number generation means at this transition,
The waiting time in the next waiting step 4 is selected in two ways, long and short. In the standby step 4, the process waits for the time determined in the connection confirmation step 3 and transitions to a connection notification location determination step 5. The reason why a plurality of standby times are set here is that when a communication node to be notified of a connection is determined in the next step, the determination is made at random.

The connection notification location determination step 5 is a step for determining one communication node to which a connection notification is to be transmitted from among the connectable node groups.
FIG. 11 shows a flowchart of the connection notification portion determination step 5. In FIG. 11, if there is no connectable adjacent communication node in step 20, the process proceeds to the connection step 2 via the connection notification determination step 8.

There is a connectable adjacent communication node, and a connection request (RX_CONNECT) from another communication node
_REQUEST) has not been received (step 2
In 1), a connection request (TX_CONNECT_REQUEST) is sent to all adjacent communication nodes that can be connected.
ST) is transmitted (step 22). Connection request (TX_
CONNECT_REQUEST) is represented by a line state where A = 0 and B = Z. Connection permission (RX_CONNECT_GRAN) at all ports that transmitted the connection request
T, A = 0, B = 1) (step 23),
The communication node that performs the connection notification randomly determines the port to be transmitted as described above, and transitions to connection step 2.

Before the communication node transmits a connection request, it receives a connection request from an adjacent communication node (step 2).
1) The communication node transmits a connection request to a connectable adjacent communication node other than the requesting node to repeat the request (step 27) (step 28).
Then, when connection permission (RX_CONNECT_GRANT) is received by all ports that have transmitted the connection request (step 29), connection permission (TX_CONNECT_GRANT, A = 1, B) is received from the port that received the connection request.
= Z) and repeats (step 36).

If there is only a connection request from a connectable adjacent communication node (step 27), a connection permission is transmitted to the requesting adjacent communication node (step 37). The communication node that has transmitted the connection permission determines the standby time as described above, and transitions to standby step 4.
If no connection permission has been received, it is determined whether a plurality of connection requests have been received simultaneously (step 30). If a plurality of connection requests have been received, a connection request is transmitted to the adjacent communication node that has issued the connection request, By creating a contention state of the request, a contention due to a plurality of receptions is notified (step 38). Then, the conflict notification ends (RX_CONTEND_END, A
= 0, B = Z line state) Upon reception (step 39), the connection request returns to a state where transmission or repeat is possible.

If not received, a connection request conflict (RX_REQUEST_CONTEND, A = 0, B
= 0 (line state of 0) is received (step 31), and if not received, the request is repeated.
If received, the transmission of the connection request is stopped (step 32). In addition, in order to notify the node that has started transmitting the connection request of the contention, a connection request is transmitted to the adjacent communication node that has issued the connection request, and a contention state of the request is created, so that contention due to multiple receptions can be performed. Notify (Step 3
3). Then, upon reception of the race condition notification end (step 34), the state returns to the state in which the connection request can be transmitted or repeated again.

If the communication node that has initiated the connection request in step 22 receives a request conflict (step 2)
4) In order to determine the node that can overcome the competition as randomly as possible, the waiting time is selected from two types of long and short according to the least significant bit of the random number given by the random number generating means (step 25), and the selected waiting time and request The transmission from the port receiving the conflict is stopped (step 26). If a connection request is received during standby, it is determined that the contention has been lost (step 27), and the connection request is repeated to other adjacent communication nodes (step 30). If no connection request is received after the elapse of the standby time, a connection request is made again (step 22). The difference between the long waiting time and the short waiting time needs to be equal to or more than the sum of the request contention and the time for repeating the connection request between the requesting communication nodes. This is to prevent the other party from starting the connection request while the connection request is being repeated, even if there is a difference in the length of the waiting time, so that the winning or losing of the competition cannot be determined.

Regarding the connection notification point determination step 5,
There is also an implementation method as shown in the flowcharts of FIGS. According to this method, a local node in a node group is determined according to a method of determining a root node in accordance with the IEEE 1394 standard, and a communication node having a candidate for a location to perform a connection notification is assigned to this local node. This is a method in which a connection request is made, and a local root node grants a connection to the request.

In the process of determining the local root node, the communication node that determines in step 50 that there is only one port logically connected in the connection notification point determination step 5 PARENT_NOTI
The signal FY is transmitted. Step 5 of each communication node
The number of ports that received this PARENT_NOTIFY at 1 is counted, and if this is greater than or equal to the number of logically connected ports minus one, PARE
CHI to the communication node that sent NT_NOTIFY
Child hands sending LD_NOTIFY
Perform a hake to determine that they are their local child nodes (step 52).

When the communication node that has transmitted PARENT_NOTIFY stops transmitting PARENT_NOTIFY, if the count of the number of ports that received PARENT_NOTIFY is the same as the number of logically connected ports, the local root node Is determined (step 53), otherwise Paren
Move to step 54 of t Handshake. Here, PARENT_N is used for logically connected ports.
PARENT_ from the port that did not receive OTIFY
NOTIFY, and the adjacent communication node
When HILD_NOTIFY is transmitted, it is determined that this adjacent communication node is a local parent node, and PAREN
The transmission of T_NOTIFY is stopped. If the adjacent communication node has also transmitted PARENT_NOTIFY (step 55), a standby time is selected using random number generation means (step 70), and after standby (step 71), PARE is performed.
Child Hand when receiving NT_NOTIFY
Perform a shake to become the local root node, otherwise retry the Parent Handshake (step 72). The local root node is determined as described above.

When the local root node is determined, the local root node transmits a route determination notification to notify the node group within the node group (step 73), and the node receiving the notification repeats the notification (step 58). .
After that, each node selects a standby time using the random number generation means (step 74 for the route, step 59 for the others), and then waits (step 75 for the route, step 60 for the others). The reason why the waiting time is selected by a random number is to prevent a communication node close to the local root node from being selected only when a connection is requested.

After the elapse of the waiting time, if a connection request has been received (step 76), the local root node transmits a connection permission from the port that received the connection request (step 7).
9), a connection notification location determination notification is transmitted on the other logically connected ports (step 81). The other nodes repeat the connection request to the local parent node, and transmit a connection notification location determination notification on the other logically connected ports (step 66). When the communication node that has repeated the connection request receives the connection permission (step 67), the communication node repeats the connection permission to the local child node that has issued the connection request (step 68), and the other logically connected ports Transmits a connection notification location determination notification (step 69).

When the connection notification location determination notification is received, the connection notification location determination notification is transmitted from all logically connected ports (step 69). If the local root node does not receive the connection request after the elapse of the waiting time, among the communication nodes having ports that can perform the connection notification, the local root node receives the connection notification location determination notification, The connection notification location determination notification is transmitted from all logically connected ports (step 81), and the process proceeds to the connection step 2. If the other communication nodes do not receive the connection request, the connection request is transmitted to the local parent node (step 63). If the connection permission is received, the process proceeds to connection step 2. If the connection notification location determination notification is received, the process waits. Transition to step 4.

If the communication nodes other than the local root node do not receive the connection request after the elapse of the standby time, the communication node having no port capable of performing the connection notification receives the connection notification location determination notification (step 62, 65) A connection notification location determination notification is transmitted on all logically connected ports other than the received port (step 69), and the process proceeds to the standby step 4. When the connection notification is received, repeat this. As described above, the communication node that performs the connection notification is determined.

In the latter method, arbitration is performed at high speed when there are a large number of communication nodes requesting connection. When a sufficient time has passed by repeating the above processing, all the communication nodes on the bus have formed one node group. In the waiting step 4, if the time since the start of the topology correction phase 10 exceeds the topology correction time (step 7), the information on the connection is fixed, the topology correction phase 10 is terminated, and normal initialization is performed. Return to phase.

The cable physical layer defined by IEEE 1394 is generally composed of ports, receivers, transmitters, state machines, link interfaces, and random number generating means. However, the above-described topology modification method does not rely on software processing but hardware. The connection relation can be constructed only by changing the state machine configured by logic.

Here, a description will be given of the relation between logically invalidating the connection relation of the nodes and reconstructing the connection relation, and the wiring in the actual hardware configuration. Disabling the connection is to clear the flag related to the connection of the port of the state machine, and rebuilding it is equivalent to setting the necessary flag. I do. In order to realize such processing, it is not necessary to change an analog circuit such as a port, but only to change the logic of the state machine.

As described above, according to this embodiment, once the connection relation is logically invalidated and the connection relation is logically reconstructed, the bus physically arranged in a loop is Recognition as a tree or a daisy chain has the effect of enabling communication. Also,
Since processing is performed only by exchanging signals with an adjacent communication node, it can be realized only by hardware. Further, by judging whether the connection with the adjacent communication node is possible or not based on whether or not both have notified the connection, a transmission path such as a serial cable which can transmit only limited information can be realized. Also, communication nodes determined to be connectable belong to the same node group,
By notifying the connection from only one port from one node group, it is possible to prevent a loop from being formed in the process of reconfiguring the topology without exchanging information with a remote node. Also, in the connection notification location determination step, a node in a loop having a port forming a loop that is not yet connectable to an adjacent communication node transmits a connection request, and thus a candidate for a node that performs connection notification within a short time in a node group Can be determined. Also, in the connection notification location determination step, the request of the communication node that has made the connection request first is prioritized and repeated to other adjacent communication nodes, so that the request can be sent at high speed on a transmission path where much information cannot be given. Propagation and arbitration can be performed.
Also, in the connection notification location determination step, by obtaining connection permission for all communication nodes in the direction in which the connection request was repeated and performing connection notification, it is possible to determine a node that performs connection notification without determining a route or the like. .

Also, by starting connection permission from a communication node having no destination to repeat a connection request in the connection notification location determination step, it is possible to determine a node for which connection notification is to be performed without determining a route or the like. In addition, in the connection notification location determination step, the request can be retried by transmitting the connection request to the communication node that has made the connection request at the same time and creating a contention state of the request.

In the connection notification location determination step, the random number generating means randomly determines the waiting time until the connection request is resumed from the observation of the conflict of the connection request, thereby eliminating the regularity of the arbitration result of the connection request. be able to. Also,
In the connection notification point determination step, the difference in the waiting time until resuming the connection request from the observation of the conflict of the selected connection request is sufficient to cause the signal to reciprocate between the farthest communication nodes on the bus. Due to the time, when the selection result of the standby time is different, it is possible to reliably determine the winning or losing of the competition. In addition, by determining a local root node in the node group in the connection notification location determination step, arbitration of connection requests from a large number of communication nodes can be performed at high speed.

In the connection step, the port for transmitting the connection notification is determined at random from the ports constituting the loop having no connectable adjacent communication node, so that the port selected as the connection notification port is determined. Regularity can be eliminated. In the waiting step, the waiting time is determined at random using random number generating means, thereby eliminating the regularity of the node selected as the connection notification node, thereby forming an infinite loop in which no connectable pattern appears. It can be prevented from falling.

Also, a connection confirmation is transmitted from a port determined to be connectable to the adjacent communication node, and it is determined in the connection confirmation step whether connection with the adjacent communication node is possible.
It is possible to eliminate a discrepancy in the determination of the connection possibility due to the clock phase shift between the communication nodes. Further, by ending the topology correction processing after a lapse of a predetermined time from the detection of the loop, the processing can be completed without exchanging information between distant communication nodes.

[0057]

According to the topology correction method according to the first aspect of the present invention, by temporarily invalidating the connection relation and logically reconstructing the connection relation, the bus physically arranged in a loop can be replaced. Recognition as a tree or a daisy chain has the effect of enabling communication. Also,
Since processing is performed only by exchanging signals with an adjacent communication node, it can be realized only by hardware.

According to the topology correction method of the second aspect, the possibility of connection with an adjacent communication node is determined based on whether or not both have sent connection notices, so that limited information such as a serial cable can be obtained. It can be realized even with a transmission path that can only transmit. According to the topology correction method of the third aspect, the communication nodes determined to be connectable belong to the same node group, and the connection notification is performed only from one port from one node group, so that the remote nodes are separated. It is possible to prevent a loop from being formed in the process of reconfiguring the topology without exchanging information.

According to the topology correction method of the fourth aspect, in the connection notification point determination step, the node in the loop having a port forming a loop that is not yet connectable to an adjacent communication node transmits a connection request. It is possible to determine a candidate for a node that performs a connection notification within a node group in time. According to the topology correction method according to the fifth aspect, in the connection notification location determination step, the request of the communication node which has made the connection request first is prioritized and repeated to other adjacent communication nodes, thereby increasing the amount of information. Request transmission and arbitration can be performed at high speed on a transmission path that cannot be used.

According to the topology correction method of the sixth aspect, in the connection notification location determination step, the connection is permitted by all the communication nodes in the direction in which the connection request is repeated, and the connection notification is performed to determine a route or the like. The node that performs the connection notification can be determined without the need. According to the topology correction method of the seventh aspect, in the connection notification location determining step, the connection is started from a communication node having no destination to repeat the connection request, so that the node that performs the connection notification without determining a route or the like. Can be determined.

According to the topology correction method of the present invention, the connection request is transmitted to the communication node that has simultaneously requested the connection in the connection notification point determination step, thereby creating a request conflict state. The request can be retried. According to the topology correction method of the ninth aspect, in the connection notification location determining step, the random number generation means randomly determines the waiting time from the observation of the contention of the connection request to the restart of the connection request, so that the connection request is determined. The regularity of the arbitration result can be eliminated.

According to the topology correction method of the present invention, in the connection notification point determination step, the difference in the waiting time from the observation of the conflict of the selected connection request to the restart of the connection request is the longest on the bus. Since the time is long enough to reciprocate the signal between the communication nodes and repeat, when the selection result of the standby time is different, it is possible to reliably determine the winning or losing of the competition.

According to the topology correction method of the present invention, by arbitrating connection requests from a large number of communication nodes by determining a local root node in the node group in the connection notification point determining step. Can be done. According to the topology correction method according to the twelfth aspect, in the connection step, the port for transmitting the connection notification is determined at random from the ports constituting the loop having no connectable adjacent communication node, thereby establishing the connection. The regularity of the port selected as the notification port can be eliminated.

According to the topology correction method of the thirteenth aspect, in the waiting step, the waiting time is determined randomly by using the random number generation means, thereby eliminating the regularity of the node selected as the connection notification node. It is possible to prevent an infinite loop in which a connectable pattern does not appear. According to the topology correction method according to claim 14, each communication node is transmitted by transmitting a connection confirmation from a port determined to be connectable to the adjacent communication node and determining whether connection is possible with the adjacent communication node in the connection confirmation step. It is possible to eliminate a discrepancy in the determination of connection possibility due to a phase difference between clocks.

According to the topology correction method of the present invention, the processing of the topology correction is terminated after a lapse of a predetermined time from the detection of the loop, thereby completing the processing without exchanging information between distant communication nodes. Can be.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining a topology correction method according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a state where communication nodes are arranged in a loop.

FIG. 3 is a schematic diagram showing a state in which a logical connection between communication nodes has been invalidated.

FIG. 4 is a schematic diagram showing a state in which a connection notification is being transmitted.

FIG. 5 is a schematic diagram showing a state where connection is determined to be possible by a connection notification.

FIG. 6 is a schematic diagram showing a state in which communication nodes determined to be connectable form a node group.

FIG. 7 is a schematic diagram showing a state in which a node group increases the number of components.

FIG. 8 is a schematic diagram showing a state in which the entire bus is in one node group.

FIG. 9 is a schematic diagram showing a case where the communication node 0 first determines that connection is possible.

FIG. 10 is a schematic diagram illustrating a case where the communication node 1 first determines that connection is possible.

FIG. 11 is a flowchart illustrating a specific example of a connection notification location determination step by a method that does not determine a local root node.

FIG. 12 is a flowchart illustrating an upper half of a specific example of a connection notification point determination step according to a method of determining a local root node.

FIG. 13 is a flowchart illustrating a lower half of a specific example of a connection notification point determination step according to a method of determining a local root node.

[Explanation of symbols]

 1 Loop detection step 2 Connection step 3 Connection confirmation step 4 Standby step 5 Connection notification location determination step 100-102 Communication node 103-108 Port 110-112 Transmission path 113,114 Node group 115-119 Connection notification

Claims (15)

[Claims] In a bus configured by a plurality of communication nodes and a transmission path connecting the communication nodes, when the communication nodes are connected in an arrangement including a loop by the transmission path, each of the communication nodes is connected to a loop. In the detection step, it is determined whether the communication node is included in the loop, and the communication node in the loop, which is the communication node configuring the loop, temporarily invalidates the connection of the transmission path, and is connected by the transmission path in the connection step. Among the communication nodes, a connection notification is transmitted to an adjacent communication node that constitutes a loop, and it is determined whether or not the adjacent communication node can be connected without forming a logical loop, A topology correction method characterized in that a logical connection is made valid at a location determined to be connectable. 2. The method according to claim 2, wherein, in the connecting step, when the adjacent communication node also transmits the connection notification on the transmission path on which the communication node in the loop is transmitting the connection notification, the loop does not logically form a loop. 2. The topology correction method according to claim 1, wherein it is determined that connection with an adjacent communication node is possible. 3. In the connecting step, if the in-loop communication node determines that it can newly connect to an adjacent communication node without logically forming a loop, the in-loop communication node has already formed the connectable communication node. A new node group formed by the communication nodes and the node group formed by the adjacent communication node newly determined to be connectable form the same node group, and the one node 2. The topology correction method according to claim 1, wherein a connection notification is transmitted from a group at a maximum of one port. 4. In the connection notification location determination step, when there is at least one port that is not yet connectable to an adjacent communication node, the in-loop communication node issues a connection request requesting that the communication node be a communication node that performs connection notification. 2. The topology correction method according to claim 1, wherein, after transmitting the connection request, if it is determined that a connection notification is possible, the process proceeds to a connection step. 5. When the connection request is received before the in-loop communication node transmits the connection request in the connection notification location determination step, the connection request is transmitted to a port constituting a loop other than the connection request. The topology modification method according to claim 4, wherein the transmission is performed. 6. In the connection notification point determining step, when the in-loop communication node receives connection permission at all ports to which the connection request has been transmitted, the loop communication node receives the connection request from the adjacent communication node before transmitting the connection request. If a connection request has not been received, it is determined that a connection notification is possible, and the process proceeds to a connection step.If the connection request has been received, the connection permission is transmitted at a port that has received the connection request. 4. The topology correction method according to 4. 7. In a connection notification location determining step, when one port has received a connection request and there are no other ports constituting a loop, transmitting a connection permission at the port receiving the connection request. 5. The topology correction method according to claim 4, wherein: 8. The method according to claim 4, wherein in the connection notification location determining step, when it is determined that a plurality of connection requests have been received at the same time, the connection request is transmitted from a port that has received the connection request. Topology modification method. 9. In the connection notification location determining step, when a conflict of the connection request is observed at the port that has transmitted the connection request, the communication node in the loop that has started transmitting the connection request by itself is provided with random number generation means. 5. The topology correction method according to claim 4, wherein transmission at the port that transmitted the connection request is stopped for a standby time selected based on the random number obtained. 10. The connection notification point determining step, wherein a difference between standby times selected based on a random number given by a random number generating means causes a signal to reciprocate on a transmission path having a length corresponding to the longest path of a bus. 10. The topology correction method according to claim 9, wherein the time is equal to or longer than a time required for the topology. 11. A connection notification location determining step, in which a local root node is determined in the node group, a connection request is made to the local root node, and the local root node starts transmitting a connection permission. 2. The topology correction method according to claim 1, wherein 12. When the connection notification becomes possible in the connection notification location determination step, the port for performing the connection notification is given by the random number generation means from the ports constituting the loop and not yet in a connectable state. 5. The topology correction method according to claim 4, wherein the selection is made based on a random number. 13. The topology correction method according to claim 1, wherein the waiting time in the waiting step is determined from a plurality of times based on a random number given by the random number generating means. 14. A connection confirmation step immediately after the connection step, wherein the connection confirmation step determines whether connection with an adjacent communication node is possible, and the connection step immediately before the connection step allows connection with the adjacent communication node. 2. The topology correction method according to claim 1, wherein when it is determined that the adjacent communication node determines that the adjacent communication node can connect to itself, the connection confirmation is transmitted. 15. The topology correction method according to claim 1, wherein if the time required for the topology correction has elapsed since the loop was detected in the loop detection step, the topology correction processing is terminated.